The present invention relates generally to the use and design of optical components for communications systems. The present invention more particularly relates to electromechanical optical devices that reflect and redirect an optical signal.
Certain prior art micro-electro-mechanical systems, or MEMS, employ mirrors that are positioned by means of an electrostatic actuator. Typically an actuator tilts the mirror about a single axis. The degree of rotational freedom of the mirror is usually small and tightly limits the maximum available range of a trajectory of a reflection of a light beam. Prior art trajectories of reflected light beams are therefore typically linear, straight and short in length. The modest ranges of prior art trajectories limit the number of receiving waveguides that can be positioned to fall within the prior art trajectory. This prior art limitation in the quantity of waveguides to which the mirror can redirect an incident light beam correspondingly limits the number of light beam or optical signal channels available for optical signal transmission from the mirror.
There is, therefore, a long felt need to increase the trajectory length of the receiving plane in order to increase the number of receiving waveguides available for receiving the light beam as reflected by the movable mirror, and to increase the accuracy of positioning of the light beam on a receiving plane or an output device or waveguide.
It is an object of the present invention to provide a method and apparatus that increases the length of a trajectory located within a receiving plane for the reflection of a light beam from a movable mirror by movement of the mirror in more than one dimension.
It is an object of certain alternate preferred embodiments of the present invention to provide a method and apparatus that increases the accuracy of redirecting a light beam from the movable mirror and onto a receiving plane of the reflected light beam.
It is an object of certain still alternate preferred embodiments of the present invention to provide a method and apparatus that increases the number of light beam receiving positions available to receive the reflected light beam, whereby the number of channels transmitting the reflected light beam from the apparatus is increased.
It is an additional object of certain other preferred embodiments of the present invention to provide a method and apparatus that decreases the driving voltage required to move a movable mirror.
It is an object of certain alternate preferred embodiments of the present invention to provide a method and apparatus that includes and comprises an electro-mechanical semiconductor device to reflect and redirect an optical signal.
It is an object of certain further alternate preferred embodiments of the present invention to provide a method and apparatus that comprises a micro-electro-mechanical system, or MEMS, to reflect and redirect an optical signal.
It is an object of certain further alternate preferred embodiments of the present invention to provide a method and an apparatus that provides a micromirror that reflects an optical signal along a circular reflection pathway.
It is an object of certain still further alternate preferred embodiments of the present invention to provide a method and an apparatus that provides a micromirror that reflects an optical signal within a circular area, or another suitable surface area shape known in the art.
It is an object of certain yet alternate preferred embodiments of the present invention to provide a method and an apparatus that provides a micromirror having a pivot point and that enables the movement of the micromirror in least one rotational degree of freedom.
It is an object of certain yet alternate preferred embodiments of the present invention to provide a method and an apparatus comprising a micromirror and that enables a micromirror to move within at least two degrees of freedom.
It is an object of certain yet other alternate preferred embodiments of the present invention to provide a method and an apparatus comprising a micromirror, wherein the apparatus enables a micromirror to move from one discrete position to at least one other discrete position.
According to the method of the present invention, a rolling mirror, having a movable micromirror is provided. The invented rolling mirror redirects a light beam in a trajectory, where the trajectory lies within a receiving plane. Various alternate preferred embodiments of the invented rolling mirror generate trajectories having a suitable two dimensional shape known in the art, for example as selected from the group of shapes consisting of a circle, a substantially circular shape, a partially circular shape, and an ellipse.
A preferred embodiment of the invented rolling mirror includes a movable micromirror having a body, a reference surface, an actuator, a suspension element and an optional pivot point. The actuator is operatively coupled with the micromirror and applies force to move the micromirror. The micromirror moves along a path of motion that includes at least one section within which the motion of the micromirror is guided by contact with the reference surface. As the micromirror moves about the reference surface a reflection of a light beam incident to the micromirror is reflected at a movable point within a certain trajectory of a receiving plane. This trajectory is partially determined by the shape of the body of the micromirror and the shape of the reference surface. The reference surface may have one, two, or a plurality of sections. A section may comprise one, two or a plurality of suitable surface shapes known in the art, to include a plane surface, a conical surface, a curved surface, an arced surface, a ramped surface, a spiraled ramp surface and a helical surface.
The micromirror has a reflecting surface and a body with a contact edge, and an optional micromirror pivot feature. The contact edge may be located on or proximate to a periphery of the micromirror or the reflecting surface, or alternatively, in certain alternate preferred embodiments of the present invention the contact edge may be located on the micromirror body in a path that is of uniform or of varying distance from the periphery of the micromirror or the reflecting surface. The reflecting surface may be a concave, convex or flat reflecting surface in various preferred embodiments of the present invention. The micromirror may be shaped as a relatively thin body having a larger two-dimensional reflecting surface. Alternatively, the micromirror may have a cone shaped body or a frustum shaped body, or a body shaped according to another suitable shape known in the art.
Certain alternate preferred embodiments of the present invention comprise a micromirror body having two or more body layers, where at least two body layers have different cross-sectional sizes or shapes. Certain alternate preferred embodiments of the present invention comprise a cone-like micromirror body, where the cone-like micromirror body is similar to, or topographically equivalent to, or contained within a conical bounding cone. The cone-like micromirror body may have two or more micromirror body layers. The micromirror body layers have different cross-sectional sizes, and the smaller of two body layers, or the smallest body layer of a plurality of body layers, is positioned closer to a center of the actuator or a plurality of actuators.
The actuator of the preferred embodiment may be a suitable actuator known in the art, to include one, two or a plurality of actuators selected from the group consisting of an electro-static actuator, a piezo-electric actuator, a thermo-mechanical actuator, an electromagnetic actuator, and a polymer actuator, or other suitable actuators known in the art. One or more polymer actuators may be selected from the group consisting of an electro-active polymer actuator, an optical-active polymer, a chemically active polymer actuator, a magneto-active polymer actuator, an acousto-active polymer actuator and a thermally active polymer actuator, or other suitable polymer actuators known in the art.
Certain preferred embodiments of the present invention comprise an actuator assembly, where the actuator assembly has two or more actuator layers, where at least two actuator layers have different cross-sectional sizes or shapes. Certain alternate preferred embodiments of the present invention comprise an actuator comprising a plurality of low profile layers, where the height of most of the layers is small in comparison to the remaining two dimensions of the layer""s cross section, and the layers are assembled together to be contained within a conical bounding surface, and/or the actuator has a shape that is substantially topologically similar to, or equivalent to, a cone.
The suspension element is operatively coupled with the micromirror and provides a restoring force that returns the micromirror to a zero actuation position when the actuator provides no force, or force below a minimum level to the micromirror. The suspension element may be or comprise one or more suitable suspension components known in the art, or as selected from the group consisting of a spring, a beam, a tether, and a diaphragm. The suspension element may be at least partly flat, corrugated and/or perforated.
In certain alternate preferred embodiments of the present invention the movable micromirror and the reference surface are pivotably coupled wherein the micromirror moves in two dimensions about a pivot point as the actuator moves the micromirror.
Certain alternate preferred embodiments of the present invention are integrated on a single substrate. Certain still alternate preferred embodiments of the present invention are incorporated as micro-electro-mechanical systems, or MEMS, or a MEMS device.
In operation, the micromirror of certain preferred embodiments is moved about the pivot point while maintaining a point of contact between the contact edge and the reference surface. The position of the micromirror is determined by forces provided by the actuator and the suspension element. The point of contact between the micromirror and the reference surface shifts along the contact edge and along the reference surface as the micromirror moves.
Other objects, features, and advantages of the present invention will be apparent from the accompanying drawings and from the detailed description which follows below.